<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>typeof</title>
		<script type="text/javascript">
			let s1 = 30;
			let s2 = "张三";
			let s3 = true;
			let s4;
			let s5 = null;
			console.log("s1数据类型是：" + typeof(s1));
			console.log("s2数据类型是：" + typeof(s2));
			console.log("s3数据类型是：" + typeof(s3));
			console.log("s4数据类型是：" + typeof(s4));
			console.log("s5数据类型是：" + typeof(s5));
		</script>
	</head>
	<body>
	</body>
</html>